Contaminant Transport & Flow Through Fractures

Non-aqueous phase liquids (NAPLs) are among the most common groundwater contaminants. Due to their low solubilities in water, NAPLs travel through the subsurface as separate liquid phases, resulting complex multi-phase clean-up problems. Their behavior in porous media and potential methods of remediation, have been the subject of active research for the past decade. However, the characterization of NAPL flow in fractured rock has lagged behind, and the potential effectiveness of remediation techniques remains unclear. The primary reason for this uncertainty is an insufficient understanding of the basic parameters controlling NAPL flow and distribution in natural fractures. While it is generally understood that flow and distribution of NAPL within single natural fractures are controlled by aperture distribution and connectivity, little experimental work has been done to characterize these attributes.

The primary goals of the research program at the University of Buffalo are to:

1) Characterize the aperture distribution of single natural fractures with a variety of different origins.

2) Establish the sensitivity of flow to changes in aperture geometry

3) Explore the effect of changes in surface wettability

4) Determine the effectiveness of different remedial methods

To do this we are using translucent epoxy casts of single natural fractures and using a digital camera to determine aperture and actively record flow. In addition, because plastic has significantly different wetting characteristics than natural rock, the surfaces of the replicates will be modified using Radio Frequency Glow Discharge Plasma treatment.

The above picture is an aperture distribution image for a fractured dolomite sample that is approximately 11 cm by 14 cm. The largest apertures are almost black, while the areas of contact are represented by bright yellow.